Influence of Training Time and Temperature on Shape Memory Effect in Cu-Zn-Al Alloys

摘要

The influence of training temperature on the shape memory effect (SME) for the CuZnAl shape memory alloy (SMA) has been studied. It is found that there exists an optimum upper training temperature resulting in the best SME which is about 353 K for the Cu-26Zn-4Al alloy. The preferential oriented martensitic variants will be formed during cooling, since there are aligned dislocations (resulting in the best two-way memory effect (TWME)) in the parent phase after training between 293 and 353 K. However, the TWME drops gradually due to the generation of dislocation tangles in the parent phase as the training temperature increases to 373 K. Further work on the effect of training time on the SME shows that the shift of A_s temperature is little when alloys studied are trained at the optimum temperature for 15 to 40 seconds and there exists a certain training time without any shift of A_s temperature after 1000 thermal cyclings.